let checkvalue='outer value';
function checkScope(){
    let checkvalue='inner value';
    function f(){
        return checkvalue;
    }
    return f();
}

let ret1=checkScope();
console.log(ret1);

let scope='outer scope';
function checkScope(){
    let scope='inner scope';
    function f(){
        return scope;
    }
    return f;
}

let ret2=checkScope()();
console.log(ret2);

let a={
    i: 1,
    // valueOf: function(){
    //     console.log('diao yong le valueof');
    //     return a;
    // },
    toString: function(){
        console.log('diaoyongle tostring');
        return this.i;
    }
}
let b=a;
console.log(a+11);

let a1=true;
console.log(a1.toString());
console.log('隔断========================');
console.log(100*9.8);
console.log(1.335.toFixed(2));